The Histology Laboratory of the Laboratory of Pathology (LOP) is a core facility devoted to supporting the clinical activities of LOP. This consists of accessioning human tissues removed at surgery or in clinics, processing the tissues, preparing and staining slides for microscopy. Pathology residents are trained in techniques of gross dissection and learn to evaluate large and small specimens in preparation for microscopic evaluation. The lab also processes slides and blocks submitted from laboratories outside the NIH on NIH patients or non-NIH patients. Within the LOP, the Histology lab serves the Surgical Pathology, Hematopathology, Postmortem Pathology and Cytopathology sections as well as the Specialized Diagnostics Unit. To date during this fiscal year, over 20,000 tissue blocks were prepared and over 100,000 slides were cut and stained. The laboratory processes a large variety of tissue specimens from NIH patients, including a wide variety of malignancies, AIDS-related diagnostic speciment, infections, and surveillance biopsies. Additionally, the laboratory processes case material sent in consultation or for review prior to protocol entry for patients in the Clinical Center. So far during this fiscal year almost 80,000 consult slides and 3300 blocks on over 4800 cases were received. Although about 95% of effort is devoted to clinical duties, the Histology Laboratory also performs recuts of tissue blocks and does some routine staining for research projects in NCI by arrangement. This activity is coordinated with the tissue research request function of Clinical Operations. The Histology Lab does not conduct primary research but supports the activities of many investigators.